Method for testing mask articles

ABSTRACT

A method for testing a mask article includes steps of electrically connecting the mask article to an electrical sensor, applying a bias voltage to a plurality of testing sites of the mask article with a conductor, measuring at least one current distribution of the testing sites with the electrical sensor, and determining the quality of the mask article by taking the at least one current distribution into consideration.

This is a divisional application of U.S. patent application Ser. No.13/549,452 filed on Jul. 14, 2012, which claimed a priority to the U.S.provisional application Ser. No. 61/646,447, filed on May 14, 2012.

BACKGROUND

1. Technical Field

The present disclosure relates to a method for testing a mask article,and more particularly, to a method for testing a mask article byapplying an electrical bias across the mask article and measuring thecorresponding current distribution of the mask article.

2. Description of Related Arts

Semiconductor photolithography processes utilize masks for patterning.Conventionally, mask designers manufacture masks according to integratedcircuit (IC) designs in semiconductor industries or thin film transistor(TFT) designs for liquid crystal display (LCD) and color filter (CF)designs in photoelectronic industries or printed circuit board (PCB)designs obtained from IC, TFT, LCD, CF, PCB designers/clients. Afterfinishing the masks, the mask designers will provide the IC, TFT, LCD,CF, PCB designers and/or clients with defect maps for showing thelocations of mask defects on a corresponding wafer or a photoelectronicsubstrate (e.g. glass substrate) onto which mask patterns of the maskswill be transferred.

A mask defect on a mask is anything that is different from a desiredmask pattern and that occurs during the mask manufacturing process.Typically, the above defects on the mask can be inspected, for instance,by scanning the surface of the finished mask with a high resolutionmicroscope or an inspection machine and capturing images of the mask.The next step is determining whether or not the inspected mask is goodenough for use in the lithography process. This step can be performed bya skilled-inspection engineer, or by fabrication workers possibly withthe aid of inspection software. If there are no defects, or defects arediscovered but determined to be within tolerances set by themanufacturer or end-user, then the mask is passed and used to expose awafer or photoelectronic substrate. If defects are discovered and falloutside tolerances, then the mask fails the inspection, and a decisionmust be made as to whether the mask may be cleaned and/or repaired tocorrect the defects, or whether the defects are so severe that a newmask must be manufactured.

As a result of the continuous progression of smaller pattern design,even very small defects in the mask or the mask blanks can negativelyaffect production yields. For example, the major challenge for ExtremeUltraviolet lithography (EUVL) is how to provide a defect-free maskblank; i.e., how to detect the nano-scale defects on the mask blank.However, the conventional defect detection system cannot meet theprecision requirements resulting from the continuous progression ofsmaller pattern design. Hence, there is a need for a defect detectionsystem that addresses the inefficiency arising from the existingtechnology.

SUMMARY

One aspect of the present disclosure provides a method for testing amask article by applying an electrical bias across the mask article andmeasuring the corresponding current distribution of the mask article.

A method for testing a mask article according to one embodiment of thepresent disclosure comprises the steps of electrically connecting themask article to an electrical sensor, applying a bias voltage to aplurality of testing sites of the mask article with a conductor,measuring at least one current distribution of the testing sites withthe electrical sensor, and determining the quality of the mask articleby taking the at least one current distribution into consideration.

A method for testing a mask article according to another embodiment ofthe present disclosure comprises the steps of applying a bias voltage tothe mask article, electrically connecting a conductor to an electricalsensor, contacting a plurality of testing sites of the mask article withthe conductor, measuring at least one current distribution of thetesting sites with the electrical sensor through the conductor, anddetermining the quality of the mask article by taking the at least onecurrent distribution into consideration.

The foregoing is a broad outline of the features and technicaladvantages of the present disclosure in order that the detaileddescription of the following may be better understood. It should benoted that additional features and advantages of the disclosure will bedescribed hereinafter, which form the subject of the claims of thedisclosure. It should be appreciated by those skilled in the art thatthe conception and specific embodiment disclosed may be readily utilizedas a basis for modifying or designing other structures or processes forcarrying out the same purposes of the present disclosure. It should alsobe realized by those skilled in the art that such equivalentconstructions do not depart from the spirit and scope of the disclosureas set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure may be derivedby referring to the detailed description and claims when considered inconnection with the Figures, wherein like reference numbers refer tosimilar elements throughout the Figures as follows:

FIG. 1 illustrates a flow chart listing the steps for testing a maskarticle according to one embodiment of the present disclosure;

FIG. 2 and FIG. 3 are schematic diagrams illustrating the testing of amask article according to one embodiment of the present disclosure;

FIG. 4A, FIG. 5A and FIG. 6A are topographic images for three maskblanks (designated as P-0.5, P-3 and P-5);

FIG. 4B, FIG. 5B and FIG. 6B shows the current distribution images forthree mask blanks (designated as P-0.5, P-3 and P-5);

FIG. 7A is a histogram of the current distribution images (65536 datapoints in the current distribution image of 3×3 μm²) in FIG. 4B, FIG. 5Band FIG. 6B for the mask blanks (P-0.5, P-3 and P-5);

FIG. 7B shows the current distributions for lowly conductive regions inFIG. 7A;

FIG. 8A, FIG. 9A, and FIG. 10A are current distribution images for lowlyconductive regions of the mask blanks (P-0.5, P-3 and P-5);

FIG. 8B, FIG. 9B, and FIG. 10B are 3-D profiles for the mask blanks(P-0.5, P-3 and P-5);

FIG. 11 is a schematic diagram illustrating the testing of a maskarticle according to one embodiment of the present disclosure;

FIG. 12A, FIG. 13A and FIG. 14A are topographic images for three maskblanks (designated as M-0.5, M-1 and M-2);

FIG. 12B, FIG. 13B and FIG. 14B are current distribution images forthree mask blanks (designated as M-0.5, M-1 and M-2);

FIG. 15A is a histogram of the current distribution images in FIG. 12B,FIG. 13B and FIG. 14B for the mask blanks (P-0.5, P-3 and P-5);

FIG. 15B shows the current distributions for highly conductive regionsin FIG. 15A;

FIG. 16A, FIG. 17A and FIG. 18A are current distribution images forhighly conductive regions for the mask blanks (M-0.5, M-1 and M-2);

FIG. 16B, FIG. 17B and FIG. 18B are 3-D profiles for the mask blanks(M-0.5, M-1 and M-2);

FIG. 19 and FIG. 20 are schematic diagrams illustrating the testing of amask article with a multi-layer structure according to one embodiment ofthe present disclosure;

FIG. 21 and FIG. 22 are schematic diagrams illustrating the testing of amask article with a multi-layer structure according to anotherembodiment of the present disclosure;

FIG. 23 illustrates a flow chart listing the steps for testing a maskarticle according to another embodiment of the present disclosure;

FIG. 24 and FIG. 25 are schematic diagrams illustrating the testing of amask article according to another embodiment of the present disclosure;

FIG. 26 is schematic diagram illustrating the testing of a mask articleaccording to another embodiment of the present disclosure;

FIG. 27 and FIG. 28 are schematic diagrams illustrating the testing of amask article with a multi-layer structure according to anotherembodiment of the present disclosure;

FIG. 29 and FIG. 30 are schematic diagrams illustrating the testing of amask article with a multi-layer structure according to anotherembodiment of the present disclosure;

FIG. 31 and FIG. 32 are cross-sectional diagrams of a mask blank with amulti-layer structure, and the testing method of the present disclosurecan be applied to the mask blank;

FIG. 33 is cross-sectional diagram of a mask blank with a multi-layerstructure, and the testing method of the present disclosure can beapplied to the mask blank;

FIG. 34 is cross-sectional diagram of a mask blank with a multi-layerstructure, and the testing method of the present disclosure can beapplied to the mask blank;

FIG. 35 is cross-sectional diagram of a mask blank with a multi-layerstructure, and the testing method of the present disclosure can beapplied to the mask blank; and

FIG. 36 is cross-sectional diagram of a mask blank with a multi-layerstructure, and the testing method of the present disclosure can beapplied to the mask blank.

DETAILED DESCRIPTION

The following description of the disclosure accompanies drawings, whichare incorporated in and constitute a part of this specification, andillustrate embodiments of the disclosure, but the disclosure is notlimited to the embodiments. In addition, the following embodiments canbe properly integrated to complete another embodiment.

The present disclosure is directed to a method for testing a maskarticle. In order to make the present disclosure completelycomprehensible, detailed steps and structures are provided in thefollowing description. Obviously, implementation of the presentdisclosure does not limit special details known by persons skilled inthe art. In addition, known structures and steps are not described indetail, so as not to limit the present disclosure unnecessarily.Preferred embodiments of the present disclosure will be described belowin detail. However, in addition to the detailed description, the presentdisclosure may also be widely implemented in other embodiments. Thescope of the present disclosure is not limited to the detaileddescription, and is defined by the claims.

FIG. 1 illustrates a flow chart listing the steps for testing a maskarticle according to one embodiment of the present disclosure. In oneembodiment of the present disclosure, the testing method comprises astep 101 of electrically connecting the mask article to an electricalsensor, a step 103 of applying a bias voltage to a plurality of testingsites of the mask article with a conductor, a step 105 of measuring atleast one current distribution of the testing sites with the electricalsensor, and a step 107 of determining the quality of the mask article bytaking the at least one current distribution into consideration.

FIG. 2 and FIG. 3 are schematic diagrams illustrating the testing of amask article 20 according to one embodiment of the present disclosure.In an exemplary embodiment of the present disclosure, the mask article20 comprises a substrate 21 a conductive layer 23 such as a MoSi layer.In one embodiment of the present disclosure, the substrate 21 is aquartz substrate or a Ti-doped silicon oxide glass substrate. In oneembodiment of the present disclosure, the step 101 of electricallyconnecting of the mask article 20 to an electrical sensor 31 can beaccomplished by forming at least one contact 23A on the conductive layer23 of the mask article 20, and contacting a sensing probe (not shown inthe drawings) of the electrical sensor 31 with the at least one contact23A of the conductive layer 23, as shown in FIG. 2. In another exemplaryembodiment of the present disclosure, the electrical connecting of themask article 20 to an electrical sensor 31 can be accomplished byplacing the mask article 20 on a stage 10 electrically connected to theelectrical sensor 31 and forming an electrical connection between themask article 20 and the stage 10, as shown in FIG. 3. In a preferredembodiment of the present disclosure, the electrical connection betweenthe mask article 20 and the stage 10 includes the contact 23A of theconductive layer 23, a contact 10A on the stage 10 and a wire 11connecting the contact 23A and the contact 10A.

Referring to FIG. 2 or FIG. 3, in one embodiment of the presentdisclosure, the step 103 of applying a bias voltage to a plurality oftesting sites of the mask article 20 with a conductor 33 can beaccomplished by electrically connecting the conductor 33 to a biasvoltage 35 such as a voltage source and contacting the plurality oftesting sites of the mask article 20 with the conductor 33. In oneexemplary embodiment of the present disclosure, the conductor 33 is anelectrically conductive tip. In one exemplary embodiment of the presentdisclosure, the step 105 of measuring at least one current distributionof the testing sites with the electrical sensor 31 can be accomplishedby measuring the current from the bias voltage 35, through the conductor33 and the mask article 20 to the electrical sensor 31. In a preferredembodiment of the present disclosure, the steps 103 and 105 can beimplemented by contacting a first site 25A of the mask article 20 withthe conductor 33, measuring a first current value passing through thefirst site 25A of the mask article 20 with the electrical sensor 31,moving the conductor 33 to contact a second site 25B of the mask article20, measuring a second current value passing through the second site ofthe mask article 20 with the electrical sensor 33 and so on.

FIG. 4A, FIG. 5A and FIG. 6A are topographic images, and FIG. 4B, FIG.5B and FIG. 6B are current distribution images for three mask blanks(designated as P-0.5, P-3 and P-5) with a conductive layer (MoSi layer)on a quartz substrate, wherein the scanning area is 3×3 μm² with 256×256testing sites. The three mask blanks experience different cleaningprocesses at a megasonic power of 0.5 W, 3 W and 5 W, and the currentdistribution images are acquired with a bias voltage of 0.1V applied tothe conductor 33 of a conductive AFM (atomic force microscopy) duringscanning FIG. 7A is a histogram of the current distribution images inFIG. 4B, FIG. 5B and FIG. 6B. FIG. 7B shows the current distributionsfor lowly conductive regions in FIG. 7A.

For the topographic images, the Rms values are 0.118 nm, 0.140 nm and0.136 nm, and Rpv values are 0.792 nm, 1.460 nm and 1.40 nm,respectively, which indicates that their surface roughness is similar.For the current distribution images, the characteristic parametersinclude the average currents, standard deviations, and relative standarddeviations of average current, which are listed in Table 1. The standarddeviation is a root mean square of the current(I_(rms)=(Σ(Ii−Iav)²/n)^(1/2). The Relative standard deviation is equalto I_(rms)/I_(av); a smaller value indicates more uniform distributionof current.

TABLE 1 Average current Standard deviation Relative standard I_(av) (pA)I_(rms) (pA) deviation (%) P-0.5 38.8 0.9 2.3 P-3 34.2 1.40 4.1 P-5 25.61.49 5.8

FIG. 8A, FIG. 9A, and FIG. 10A are current distribution images for lowlyconductive regions for the mask blanks (P-0.5, P-3 and P-5), and FIG.8B, FIG. 9B, and FIG. 10B are 3-D profiles for the mask blanks (P-0.5,P-3 and P-5), respectively. If the area has a local current two timeslower than the average current, then it is defined as a “lowlyconductive region”. The percentage of coverage of the lowly conductiveregions on the P-0.5, P-1 and P-5 mask blanks are 0.022%, 0.121% and0.199%, respectively. The lowly conductive regions could result from theregions of defects in the MoSi layer, through which less current passesto generate a local lower current. In addition, the lowly conductiveregions for all the three mask blanks distribute randomly around thesurface of the three mask blanks. Furthermore, the lowly conductiveregions, with sizes ranging from 12 to 95 nm, can be considered defects,and thus become the origin of lowly conductive regions for CAFMmeasurement on the MoSi layer. In one embodiment of the presentdisclosure, the step 107 of determining the quality of the mask articlecan be accomplished by taking the at least one current distribution intoconsideration; for example, comparing current values of the plurality oftesting sites with the average current, and counting a number of thetesting sites with a current value lower than a threshold value such asthe average current.

FIG. 11 is a schematic diagram illustrating the testing of a maskarticle 40 according to one embodiment of the present disclosure. In anexemplary embodiment of the present disclosure, the mask article 40comprises a substrate 41, a conductive layer 43 such as a chromiumlayer, and a dielectric layer 45 such as a chromium oxide layer. In oneembodiment of the present disclosure, the step 101 of electricallyconnecting of the mask article 40 to an electrical sensor 31 can beaccomplished by forming at least one contact 43A on the conductive layer43 of the mask article 40, and contacting a sensing probe of theelectrical sensor 31 with the at least one contact 43A of the conductivelayer 43. In one embodiment of the present disclosure, the substrate 41is a quartz substrate or a Ti-doped silicon oxide glass substrate. Inanother exemplary embodiment of the present disclosure, the electricallyconnecting of the mask article 40 to the electrical sensor 31 can beaccomplished by the electrical connection similar to that shown in FIG.3.

FIG. 12A, FIG. 13A and FIG. 14A are topographic images, and FIG. 12B,FIG. 13B and FIG. 14B are current distribution images for three maskblanks (designated as M-0.5, M-1 and M-2) with a chromium oxide layerand a chromium layer on a quartz substrate, wherein the scanning area is3×3 μm² with 256×256 testing sites. The three mask blanks experiencedifferent cleaning processes at a megasonic power of 0.5 W, 1 W and 2 W,and the current distribution images are acquired with a bias voltage of0.1V applied to the conductor 33 of a conductive AFM (atomic forcemicroscopy) during scanning FIG. 15A is a histogram of the currentdistribution images in FIG. 12B, FIG. 13B and FIG. 14B, and FIG. 15Bshows the current distributions for highly conductive regions in FIG.15A.

For the topographic images, the R_(rms) values are 0.280 nm, 0.285 nmand 0.219 nm, and R_(pv) values are 2.50 nm, 2.55 nm and 2.23 nm,respectively, which indicates that their surface roughness are similar.For the current distribution images, the characteristic parametersinclude the average currents, standard deviations, and relative standarddeviations of average current which are listed in Table 2. The standarddeviation is a root mean square of the current(I_(rms)=(Σ(Ii−Iav)²/n)^(1/2). The Relative standard deviation is equalto I_(rms)/I_(av); a smaller value indicates more uniform distributionof current.

TABLE 2 Average current Standard deviation Relative standard I_(av) (pA)I_(rms) (pA) deviation (%) M-0.5 1.16 0.1 8.6 M-1 1.89 0.49 25.9 M-22.59 0.81 31.3

FIG. 16A, FIG. 17A and FIG. 18A are current distribution images forhighly conductive regions, and FIG. 16B, FIG. 17B and FIG. 18B are 3-Dprofiles for the mask blanks (M-0.5, M-1 and M-2), respectively. If thearea has a local current two times larger than the average current, thenit is defined as a “highly conductive region”. The percentage ofcoverage of the highly conductive regions on the M-0.5, M-1 and M-2 maskblanks are 0.83%, 2.57% and 5.73%, respectively. The electricalconductivity of chromium oxide layer (˜10⁴ S/m at room temperature) islower than that of the chromium layer (7.9×10⁶ S/m at room temperature).The highly conductive regions could result from the regions of damagesin the chromium oxide layer, through which current preferentially passesto generate a local higher current. In addition, the highly conductiveregions for all three mask blanks distribute randomly around theirsurfaces. Furthermore, the highly conductive regions, with sizes rangingfrom 15 to 100 nm, can be considered defects, and thus become the originof highly conductive regions for CAFM measurement. In one embodiment ofthe present disclosure, the step 107 of determining the quality of themask article can be accomplished by taking the at least one currentdistribution into consideration; for example, comparing current valuesof the testing sites with the average current, and counting a number ofthe testing sites with a current value higher than a threshold valuesuch as the average current.

FIG. 19 and FIG. 20 are schematic diagrams illustrating the testing of amask article 50 with a multi-layer structure according to one embodimentof the present disclosure. In an exemplary embodiment of the presentdisclosure, the mask article 50 is a mask blank comprising a substrate51, a first layer 53 with at least one first contact 53A, and a secondlayer 55 with at least one second contact 55A. In one embodiment of thepresent disclosure, the substrate 51 is a quartz substrate or a Ti-dopedsilicon oxide glass substrate. In a preferred embodiment of the presentdisclosure, as shown in FIG. 19, the testing method of the mask article50 comprises the steps of electrically connecting the first contact 53Ato the electrical sensor 31, applying the bias voltage 35 through theplurality of testing sites to the first layer 53 with the conductor 33,and measuring a first current distribution of the first layer 53 withthe electrical sensor 31; subsequently, as shown in FIG. 20, the testingmethod of the mask article 50 performs the steps of electricallyconnecting the second contact 55A to the electrical sensor 31, applyingthe bias voltage 35 through the plurality of testing sites to the firstlayer 53 with the conductor 33 and measuring a second currentdistribution of the second layer 55 with the electrical sensor 31. Inanother exemplary embodiment of the present disclosure, the electricalconnecting of the mask article 50 to the electrical sensor 31 can beaccomplished by the electrical connection similar to that shown in FIG.3.

In one exemplary embodiment of the present disclosure, the testingmethod of the mask article 50 determines the quality of the mask article50 by taking the first current distribution and the second currentdistribution into consideration. For example, the second currentdistribution represents the electrical effect substantially both of thefirst layer 53 and the second layer 55, while the first currentdistribution represents the electrical effect substantially of the firstlayer 53 only. Subtracting the first current distribution from thesecond current distribution substantially results in the electricalproperty of the second layer 55.

FIG. 21 and FIG. 22 are schematic diagrams illustrating the testing of amask article 60 with a multi-layer structure according to one embodimentof the present disclosure. In an exemplary embodiment of the presentdisclosure, as shown in FIG. 21, the testing method of the mask article60 comprises the steps of forming a first layer 63 with at least onefirst contact 63A on a substrate 61, electrically connecting the firstcontact 63A to the electrical sensor 31, applying the bias voltage 35through the plurality of testing sites to the first layer 63 with theconductor 33 and measuring a first current distribution of the firstlayer 63 with the electrical sensor 31. Subsequently, as shown in FIG.22, the testing method of the mask article 60 performs the steps offorming a second layer 65 with at least one second contact 65A,electrically connecting the second contact 65A to the electrical sensor31, applying the bias voltage 35 through the plurality of testing sitesto the second layer 65 with the conductor 33 and measuring a secondcurrent distribution of the second layer 65 with the electrical sensor31. In one embodiment of the present disclosure, the substrate 61 is aquartz substrate or a Ti-doped silicon oxide glass substrate. In oneembodiment of the present disclosure, the testing method of the maskarticle 60 determines the quality of the mask article 60 by taking thefirst current distribution and the second current distribution intoconsideration. In another exemplary embodiment of the presentdisclosure, the electrical connecting of the mask article 60 to theelectrical sensor 31 can be accomplished by the electrical connectionsimilar to that shown in FIG. 3.

FIG. 23 illustrates a flow chart listing the steps for testing a maskarticle according to another embodiment of the present disclosure. Inone embodiment of the present disclosure, the testing method comprises astep 201 of applying a bias voltage 35 to the mask article, a step 203of electrically connecting a conductor to an electrical sensor, a step205 of contacting a plurality of testing sites of the mask article withthe conductor, a step 207 of measuring at least one current distributionof the testing sites with the electrical sensor through the conductor,and a step 209 of determining the quality of the mask article by takingthe current distribution into consideration.

FIG. 24 and FIG. 25 are schematic diagrams illustrating the testing of amask article 20 according to another embodiment of the presentdisclosure. In an exemplary embodiment of the present disclosure, themask article 20 comprises a substrate 21 such as a quartz substrate anda conductive layer 23 such as a MoSi layer. In one embodiment of thepresent disclosure, the step 201 of applying a bias voltage 35 to themask article 20 can be accomplished by forming at least one contact 23Aon the conductive layer 23 of the mask article 20, and contacting apower probe of bias voltage 35 such as a voltage source with at leastone contact 23A of the conductive layer 23, as shown in FIG. 24.

In another exemplary embodiment of the present disclosure, the step 201of applying a bias voltage 35 to the mask article 20 can be accomplishedby placing the mask article 20 on a stage 10 electrically connected tothe bias voltage 35, and forming an electrical connection between themask article 20 and the stage 10, as shown in FIG. 25. In a preferredembodiment of the present disclosure, the electrical connection betweenthe mask article 20 and the stage 10 includes the contact 23A of theconductive layer 23, a contact 10A on the stage 10, and a wire 11connecting the contact 23A and the contact 10A.

In one embodiment of the present disclosure, the conductor 33 is anelectrically conductive tip. In one exemplary embodiment of the presentdisclosure, the step 207 of measuring at least one current distributionof the testing sites with the electrical sensor 31 through the conductor33 can be accomplished by measuring the current from the bias voltage35, through the contact 23A, the mask article 20 and the conductor 33 tothe electrical sensor 31. In a preferred embodiment of the presentdisclosure, the steps 205 and 207 can be implemented by contacting afirst site 25A of the mask article 20 with the conductor 33, measuring afirst current value passing through the first site 25A of the maskarticle 20 with the electrical sensor 31, moving the conductor 33 tocontact a second site 25B of the mask article 20, measuring a secondcurrent value passing through the second site of the mask article 20with the electrical sensor 33 and so on.

FIG. 26 is a schematic diagram illustrating the testing of a maskarticle 40 according to another embodiment of the present disclosure. Inan exemplary embodiment of the present disclosure, the mask article 40is a mask blank comprising a substrate 41 such as a quartz substrate, aconductive layer 43 such as a chromium layer, and a dielectric layer 45such as a chromium oxide layer. In one embodiment of the presentdisclosure, the step 201 of applying a bias voltage 35 to the maskarticle 40 can be accomplished by forming at least one contact 43A onthe conductive layer 43 of the mask article 40 and contacting a powerprobe of a bias voltage 35 such as a voltage source with the at leastone contact 43A of the conductive layer 43. In another exemplaryembodiment of the present disclosure, the step 201 of applying a biasvoltage 35 to the mask article 40 can be accomplished by placing themask article 40 on a stage 10 electrically connected to the bias voltage35, and forming an electrical connection between the mask article 40 andthe stage 10, as shown in FIG. 25.

FIG. 27 and FIG. 28 are schematic diagrams illustrating the testing of amask article 50 with a multi-layer structure according to anotherembodiment of the present disclosure. In an exemplary embodiment of thepresent disclosure, the mask article 50 is a mask blank comprising asubstrate 51 such as a quartz substrate, a first layer 53 with at leastone first contact 53A and a second layer 55 with at least one secondcontact 55A. In a preferred embodiment of the present disclosure, asshown in FIG. 27, the testing method of the mask article 50 comprisesthe steps of applying the bias voltage 35 to the first contact 53A,contacting the plurality of testing sites of the first layer 53 with theconductor 33, measuring a first current distribution of the first layer53 with the electrical sensor 31; subsequently, as shown in FIG. 28, thetesting method of the mask article 50 performs the steps of applying thebias voltage 35 to the second contact 55A, contacting the plurality oftesting sites of the first layer 53 with the conductor 33, and measuringa second current distribution of the second layer 55 with the electricalsensor 31.

In an exemplary embodiment of the present disclosure, the testing methodof the mask article 50 determines the quality of the mask article 50 bytaking the first current distribution and the second currentdistribution into consideration. In another exemplary embodiment of thepresent disclosure, the step 201 of applying a bias voltage 35 to themask article 50 can be accomplished by placing the mask article 50 on astage 10 electrically connected to the bias voltage 35, and forming anelectrical connection between the mask article 50 and the stage 10, asshown in FIG. 25.

FIG. 29 and FIG. 30 are schematic diagrams illustrating the testing of amask article 60 with a multi-layer structure according to anotherembodiment of the present disclosure. In one embodiment of the presentdisclosure, the testing method of the mask article 60 comprises thesteps of forming a first layer 63 with at least one first contact 63A,applying the bias voltage 35 to the first contact 63A, contacting thefirst layer 63 with the conductor 33, measuring a first currentdistribution of the first layer 63 with the electrical sensor 31, asshown in FIG. 29. Subsequently, the testing method of the mask article60 performs the steps of forming a second layer 65 with at least onesecond contact 65A, applying the bias voltage 35 to the second contact65A, contacting the second layer 65 with the conductor 33, and measuringa second current distribution of the second layer 65 with the electricalsensor 31.

In one embodiment of the present disclosure, the testing method of themask article 60 determines the quality of the mask article 60 by takingthe first current distribution and the second current distribution intoconsideration. In another exemplary embodiment of the presentdisclosure, the step 201 of applying a bias voltage 35 to the maskarticle 60 can be accomplished by placing the mask article 60 on a stage10 electrically connected to the bias voltage 35 and forming anelectrical connection between the mask article 60 and the stage 10, asshown in FIG. 25.

FIG. 31 and FIG. 32 are cross-sectional diagrams of a mask blank 70 witha multi-layer structure, and the testing method of the presentdisclosure can be applied to the mask blank 70. The mask blank 70comprises a substrate 71, a reflective multi-layer 73, a capping(protecting) layer 75 including silicon, a buffer layer 77 includingchromium and/or chromium nitride, and an absorber layer 79 includingtitanium nitride. In an exemplary embodiment of the present disclosure,the mask blank 70 is formed with at least one contact for each layer,i.e., at least one contact 73A is formed on the reflective multi-layer73, at least one contact 75A is formed on the capping layer 75, at leastone contact 77A is formed on the buffer layer 77, and at least onecontact 79A is formed on the absorber layer 79. In a preferredembodiment of the present disclosure, the contacts are formed on some ofthe layers, rather than formed on each layer.

In one embodiment of the present disclosure, the substrate 71 is aquartz substrate or a Ti-doped silicon oxide glass substrate. In oneembodiment of the present disclosure, the reflective multi-layer 73includes a Si layer 72A and a Mo layer 72B stacked in an alternatingmanner. However, the reflective multi-layer 73 is not limited thereto,but a Ru/Si multilayered reflective film, a Mo/Be multilayeredreflective film, a Mo compound/Si compound multilayered reflective film,a Si/Mo/Ru multilayered reflective film, a Si/Mo/Ru/Mo multilayeredreflective film or a Si/Ru/Mo/Ru multilayered reflective film may beemployed.

In one embodiment of the present disclosure, as the layers of the maskblank 70 are formed with at least one contact, the testing methoddescribed in FIGS. 19-20 or FIGS. 27-28 can be applied to test the maskblank 70 after the fabrication process is completed. In anotherembodiment of the present disclosure, as the layers of the mask blank 70are formed with at least one contact during the fabrication process ofthe mask blank 70, the testing method described in FIGS. 21-22 or FIGS.29-30 can be applied to test the mask blank 70 during the fabricationprocess.

FIG. 33 is cross-sectional diagram of a mask blank 80 with a multi-layerstructure, and the testing method of the present disclosure can beapplied to the mask blank 80. The mask blank 80 comprises a substrate81, a backside layer 82 such as a conductive layer including chromium, areflective multi-layer 83 including Mo and Si layers stacked in analternating manner as that shown in FIG. 32, a buffer (protecting) layer85 including chromium or chromium nitride, an absorber layer 87including titanium nitride, and a resist layer 89. In an exemplaryembodiment of the present disclosure, the mask blank 80 is formed withat least one contact for each layer, i.e., at least one contact 83A isformed on the reflective multi-layer 83, at least one contact 85A isformed on the buffer layer 85, at least one contact 87A is formed on theabsorber layer 87, and at least one contact 89A is formed on the resistlayer 89. In one embodiment of the present disclosure, the substrate 81is a quartz substrate or a Ti-doped silicon oxide glass substrate. In apreferred embodiment of the present disclosure, the contacts are formedon some of the layers, rather than formed on each layer.

In one embodiment of the present disclosure, as the layers of the maskblank 80 are formed with at least one contact, the testing methoddescribed in FIGS. 19-20 or FIGS. 27-28 can be applied to test the maskblank 80 after the fabrication process is completed. In anotherembodiment of the present disclosure, as the layers of the mask blank 80are formed with at least one contact during the fabrication process ofthe mask blank 80, the testing method described in FIGS. 21-22 or FIGS.29-30 can be applied to test the mask blank 80 during the fabricationprocess.

FIG. 34 is a cross-sectional diagram of a mask blank 90 with amulti-layer structure, and the testing method of the present disclosurecan be applied to the mask blank 90. The mask blank 90 comprises asubstrate 91, a backside layer 92 such as a conductive layer includingchromium, a reflective multi-layer 93 including Mo and Si layers stackedin an alternating manner, a capping (protecting) layer 95 includingruthenium, an absorber layer 97 including titanium nitride, and a resistlayer 99. In an exemplary embodiment of the present disclosure, the maskblank 90 is formed with at least one contact for each layer, i.e., atleast one contact 93A is formed on the reflective multi-layer 93, atleast one contact 95A is formed on the capping layer 95, at least onecontact 97A is formed on the absorber layer 97, and at least one contact99A is formed on the resist layer 99. In one embodiment of the presentdisclosure, the substrate 91 is a quartz substrate or a Ti-doped siliconoxide glass substrate. In a preferred embodiment of the presentdisclosure, the contacts are formed on some of the layers, rather thanformed on each layer.

In one embodiment of the present disclosure, as the layers of the maskblank 90 are formed with at least one contact, the testing methoddescribed in FIGS. 19-20 or FIGS. 27-28 can be applied to test the maskblank 90 after the fabrication process is completed. In anotherembodiment of the present disclosure, as the layers of the mask blank 90are formed with at least one contact during the fabrication process ofthe mask blank 90, the testing method described in FIGS. 21-22 or FIGS.29-30 can be applied to test the mask blank 90 during the fabricationprocess.

FIG. 35 is a cross-sectional diagram of a mask blank 120 with amulti-layer structure, and the testing method of the present disclosurecan be applied to the mask blank 120. The mask blank 120 comprises asubstrate 121, a backside layer 122 such as a conductive layer includingchromium, a reflective multi-layer 123 including Mo and Si layersstacked in an alternating manner, a capping (protecting) layer 125including silicon, a buffer layer 127 including chromium nitride, anabsorber layer 129 including titanium nitride, and a resist layer 131.In an exemplary embodiment of the present disclosure, the mask blank 120is formed with at least one contact for each layer, i.e., at least onecontact 123A is formed on the reflective multi-layer 123, at least onecontact 125A is formed on the capping layer 125, at least one contact127A is formed on the buffer layer 127, and at least one contact 129A isformed on the resist layer 129. In one embodiment of the presentdisclosure, the substrate 121 is a quartz substrate or a Ti-dopedsilicon oxide glass substrate. In a preferred embodiment of the presentdisclosure, the contacts are formed on some of the layers, rather thanformed on each layer.

In one embodiment of the present disclosure, as the layers of the maskblank 120 can be formed with at least one contact, the testing methoddescribed in FIGS. 19-20 or FIGS. 27-28 can be applied to test the maskblank 120 after the fabrication process is completed. In anotherembodiment of the present disclosure, as the layers of the mask blank120 can be formed with at least one contact during the fabricationprocess of the mask blank 120, the testing method described in FIGS.21-22 or FIGS. 29-30 can be applied to test the mask blank 120 duringthe fabrication process.

FIG. 36 is a cross-sectional diagram of a mask blank 140 with amulti-layer structure, and the testing method of the present disclosurecan be applied to the mask blank 140. The mask blank 140 comprises asubstrate 141, a backside layer 142 such as a conductive layer includingchromium or chromium nitride for electrostatic chuck, a reflectivemulti-layer 143 including Mo and Si layers stacked in an alternatingmanner, a capping/buffer (protecting) layer 145, an absorber layer 147,an anti-reflection layer 149, and a resist layer 151. In one embodimentof the present disclosure, the substrate 141 is a quartz substrate or aTi-doped silicon oxide glass substrate; the absorber layer 147 includesmaterial selected from the group consisting of tantalum nitride,tantalum silicon nitride, silicon oxide, tantalum, chromium nitride,tungsten, ruthenium and the combination thereof; the anti-reflectionlayer 149 includes material selected from the group consisting ofsilicon oxide, silicon nitride, aluminum oxide, silicon oxynitride andthe combination thereof. The capping/buffer layer 145 includes materialselected from the group consisting of carbon, carbon carbide, ruthenium,silicon nitride and a mixture thereof. Furthermore, the capping/bufferlayer 145 may include Cr, Al and Ta, a nitride thereof, Ru, a Rucompound (RuB, RuSi etc.), SiO₂, Si₃N₄, Al₂O₃ and a mixture thereof.Among these, it is preferred to use Ru, a Ru compound (RuB, RuSi etc.),and at least one of CrN and SiO₂, it is particularly preferred to use Ruor a Ru compound (RuB, RuSi etc.).

In an exemplary embodiment of the present disclosure, the mask blank 140is formed with at least one contact for each layer, i.e., at least onecontact 143A is formed on the reflective multi-layer 143, at least onecontact 145A is formed on the capping/buffer layer 145, at least onecontact 147A is formed on the absorber layer 147, at least one contact149A is formed on the anti-reflection layer 149, and at least onecontact 151A is formed on the resist layer 151. In a preferredembodiment of the present disclosure, the contacts are formed on some ofthe layers, rather than formed on each layer. In one embodiment of thepresent disclosure, the layers of the mask blank 140 can be formed withat least one contact for some interesting layers during the fabricationprocess of the mask blank 140, and the testing method described in FIGS.19-20 or FIGS. 27-28 can be applied to test the mask blank 140 after thefabrication process is completed. In another embodiment of the presentdisclosure, the layers of the mask blank 140 can be formed with at leastone contact for some interesting layers during the fabrication processof the mask blank 140, and the testing method described in FIGS. 21-22or FIGS. 29-30 can be applied to test the mask blank 140 during thefabrication process. In preferred embodiment of the present disclosure,the layers of the mask blank 140 are formed with at least one contactfor each layer.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims. For example,many of the processes discussed above can be implemented in differentmethodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machines,manufacture, compositions of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or stepspresently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A method for testing a mask article, comprisingsteps of: electrically connecting the mask article to an electricalsensor, wherein the mask article includes a conductive layer, and theelectrical connection is formed between the electrical sensor and theconductive layer; applying a bias voltage to a plurality of testingsites of the mask article; measuring at least one current distributionof the testing sites with the electrical sensor; and determining thequality of the mask article by taking the at least one currentdistribution into consideration, wherein the determining of the qualityof the mask article includes a step of counting a number of the testingsites with a current value lower than a threshold value.
 2. The methodfor testing a mask article of claim 1, comprising steps of: contacting afirst site of the mask article with a conductor; measuring a firstcurrent value passing through the mask article with the electricalsensor; contacting a second site of the mask article with the conductor;and measuring a second current value passing through the mask articlewith the electrical sensor.
 3. The method for testing a mask article ofclaim 1, wherein the step of electrically connecting the mask article toan electrical sensor comprises: forming at least one contact on the maskarticle; and contacting a sensing probe of the electrical sensor withthe at least one contact.
 4. The method for testing a mask article ofclaim 1, wherein the step of electrically connecting the mask article toan electrical sensor comprises: placing the mask article on a stageelectrically connected to the electrical sensor; and forming anelectrical connection between the mask article and the stage.
 5. Themethod for testing a mask article of claim 1, wherein the mask articleincludes a first layer with at least one first contact and a secondlayer with at least one second contact, the method comprising steps of:electrically connecting the first contact to the electrical sensor;applying the bias voltage to the first layer with a conductor; measuringa first current distribution of the first layer with the electricalsensor; electrically connecting the second contact to the electricalsensor; applying the bias voltage to the first layer with the conductor;and measuring a second current distribution of the second layer with theelectrical sensor.
 6. The method for testing a mask article of claim 5,wherein the determining of the quality of the mask article is performedby taking the first current distribution and the second currentdistribution into consideration.
 7. The method for testing a maskarticle of claim 1, comprising steps of: forming a first layer with atleast one first contact; electrically connecting the first contact tothe electrical sensor; applying the bias voltage to the first layer witha conductor; measuring a first current distribution of the first layerwith the electrical sensor; forming a second layer with at least onesecond contact; electrically connecting the second contact to theelectrical sensor; applying the bias voltage to the second layer withthe conductor; and measuring a second current distribution of the secondlayer with the electrical sensor.
 8. The method for testing a maskarticle of claim 7, wherein the determining of the quality of the maskarticle is performed by taking the first current distribution and thesecond current distribution into consideration.
 9. A method for testinga mask article, comprising steps of: electrically connecting the maskarticle to an electrical sensor, wherein the mask article includes adielectric layer on a conductive layer, and the electrical connection isformed between the electrical sensor and the conductive layer; applyinga bias voltage to a plurality of testing sites of the mask article;measuring at least one current distribution of the testing sites withthe electrical sensor; and determining the quality of the mask articleby taking the at least one current distribution into consideration,wherein the determining of the quality of the mask article includes astep of counting a number of the testing sites with a current valuehigher than a threshold value.
 10. The method for testing a mask articleof claim 9, comprising steps of: contacting a first site of the maskarticle with a conductor; measuring a first current value passingthrough the mask article with the electrical sensor; contacting a secondsite of the mask article with the conductor; and measuring a secondcurrent value passing through the mask article with the electricalsensor.
 11. The method for testing a mask article of claim 9, whereinthe step of electrically connecting the mask article to an electricalsensor comprises: forming at least one contact on the mask article; andcontacting a sensing probe of the electrical sensor with the at leastone contact.
 12. The method for testing a mask article of claim 9,wherein the step of electrically connecting the mask article to anelectrical sensor comprises: placing the mask article on a stageelectrically connected to the electrical sensor; and forming anelectrical connection between the mask article and the stage.
 13. Themethod for testing a mask article of claim 9, wherein the mask articleincludes a first layer with at least one first contact and a secondlayer with at least one second contact, the method comprising steps of:electrically connecting the first contact to the electrical sensor;applying the bias voltage to the first layer with a conductor; measuringa first current distribution of the first layer with the electricalsensor; electrically connecting the second contact to the electricalsensor; applying the bias voltage to the first layer with the conductor;and measuring a second current distribution of the second layer with theelectrical sensor.
 14. The method for testing a mask article of claim13, wherein the determining of the quality of the mask article isperformed by taking the first current distribution and the secondcurrent distribution into consideration.
 15. The method for testing amask article of claim 9, comprising steps of: forming a first layer withat least one first contact; electrically connecting the first contact tothe electrical sensor; applying the bias voltage to the first layer witha conductor; measuring a first current distribution of the first layerwith the electrical sensor; forming a second layer with at least onesecond contact; electrically connecting the second contact to theelectrical sensor; applying the bias voltage to the second layer withthe conductor; and measuring a second current distribution of the secondlayer with the electrical sensor.
 16. The method for testing a maskarticle of claim 15, wherein the determining of the quality of the maskarticle is performed by taking the first current distribution and thesecond current distribution into consideration.
 17. A method for testinga mask article, comprising steps of: electrically connecting the maskarticle to an electrical sensor; applying a bias voltage to a pluralityof testing sites of the mask article; measuring at least one currentdistribution of the testing sites with the electrical sensor; anddetermining the quality of the mask article by taking the at least onecurrent distribution into consideration, wherein the determining of thequality of the mask article includes a step of calculating an averagecurrent of the testing sites.
 18. The method for testing a mask articleof claim 17, comprising steps of: contacting a first site of the maskarticle with a conductor; measuring a first current value passingthrough the mask article with the electrical sensor; contacting a secondsite of the mask article with the conductor; and measuring a secondcurrent value passing through the mask article with the electricalsensor.
 19. The method for testing a mask article of claim 17, whereinthe step of electrically connecting the mask article to an electricalsensor comprises: forming at least one contact on the mask article; andcontacting a sensing probe of the electrical sensor with the at leastone contact.
 20. The method for testing a mask article of claim 17,wherein the step of electrically connecting the mask article to anelectrical sensor comprises: placing the mask article on a stageelectrically connected to the electrical sensor; and forming anelectrical connection between the mask article and the stage.
 21. Themethod for testing a mask article of claim 17, wherein the mask articleincludes a first layer with at least one first contact and a secondlayer with at least one second contact, the method comprising steps of:electrically connecting the first contact to the electrical sensor;applying the bias voltage to the first layer with a conductor; measuringa first current distribution of the first layer with the electricalsensor; electrically connecting the second contact to the electricalsensor; applying the bias voltage to the first layer with the conductor;and measuring a second current distribution of the second layer with theelectrical sensor.
 22. The method for testing a mask article of claim21, wherein the determining of the quality of the mask article isperformed by taking the first current distribution and the secondcurrent distribution into consideration.
 23. The method for testing amask article of claim 17, comprising steps of: forming a first layerwith at least one first contact; electrically connecting the firstcontact to the electrical sensor; applying the bias voltage to the firstlayer with a conductor; measuring a first current distribution of thefirst layer with the electrical sensor; forming a second layer with atleast one second contact; electrically connecting the second contact tothe electrical sensor; applying the bias voltage to the second layerwith the conductor; and measuring a second current distribution of thesecond layer with the electrical sensor.
 24. The method for testing amask article of claim 17, wherein the determining of the quality of themask article is performed by taking the first current distribution andthe second current distribution into consideration.